java 局部变量的作用域问题

[tang_123_]

public class LocalVarTest {

	public static void main(String[] args) {
		LocalVar var = new LocalVar();
		var.doNext();
	}

}

class LocalVar{
	private Scorer[] scorers;
	private boolean more;
	private int lastDoc;
	
	public boolean doNext(){
	    int first=0;
	    Scorer lastScorer = scorers[scorers.length-1];
	    Scorer firstScorer;
	    while (A.isTrue(more && (firstScorer=scorers[first]).doc() < (lastDoc=lastScorer.doc()), 1, 2)) {
	      more = firstScorer.skipTo(lastDoc);
	      lastScorer = firstScorer;
	      first = (first == (scorers.length-1)) ? 0 : first+1;
	    }
	    return more;
	}
}

class A{
	private static int[] a = new int[100];
	
	public static boolean isTrue(boolean isA, int i, int j){
		a[i] = j; 
		return isA;
	}
}

class Scorer{

	public int doc() {
		
		return 0;
	}

	public boolean skipTo(int lastDoc) {
		
		return false;
	}
}

一直报 The local variable firstScorer may not have been initialized 错误，如果把 firstScorer 赋个初值，如：
firstScorer = null
就没有问题了，现在问题是代码是动态的，不方便赋值，不知有什么方法解决？谢谢！

[ctrlzhang]

java中，类对象声明是不会产生对象实例的, 需要new出来后，才可以使用对象方法.

[baidu_28053655]

还是蒙，我是新手，好蒙

[Fatal Error]

scorers没看到有初始化啊，这个数组是空的吧。

[codingjav]

java对象先创建实例才可以调用其方法

[tang_123_]

引用 3 楼 gf0515 的回复:

scorers没看到有初始化啊，这个数组是空的吧。

不用管scorers，假设scores以及赋过值了。

[tang_123_]

引用 4 楼 jinwufeiyang 的回复:

java对象先创建实例才可以调用其方法

调用前已经赋值了。 firstScorer=scorers[first]

[tang_123_]

修改了下代码，scorers 值不为空的。

public class LocalVarTest {

	public static void main(String[] args) {
		Scorer scorer1 = new Scorer();
		Scorer scorer2 = new Scorer();
		Scorer[] scorers = {scorer1, scorer2};
		LocalVar var = new LocalVar(scorers);
		var.doNext();
	}

}

class LocalVar{
	private Scorer[] scorers;
	private boolean more;
	private int lastDoc;
	
	public LocalVar(Scorer[] scorers){
		this.scorers = scorers;
	}
	
	public boolean doNext(){
	    int first=0;
	    Scorer lastScorer = scorers[scorers.length-1];
	    Scorer firstScorer = null;
	    while (A.isTrue(more && (firstScorer=scorers[first]).doc() < (lastDoc=lastScorer.doc()), 1, 2)) {
	      more = firstScorer.skipTo(lastDoc);
	      lastScorer = firstScorer;
	      first = (first == (scorers.length-1)) ? 0 : first+1;
	    }
	    return more;
	}
}

class A{
	private static int[] a = new int[100];
	
	public static boolean isTrue(boolean isA, int i, int j){
		a[i] = j; 
		return isA;
	}
}

class Scorer{

	public int doc() {
		
		return 0;
	}

	public boolean skipTo(int lastDoc) {
		
		return false;
	}
}

[qq_31900971]

不知道你哪段代码是自动生成的，如果是doNext方法自动生成的话，那就用AOP，看是不是你想要的。 //定义接口 public interface LocalVarInterface{ public boolean doNext(); } //实现接口 public class LocalVar implements LocalVarInterface{ private Scorer[] scorers; private boolean more; private int lastDoc; public boolean doNext(){ //里面没办法了，编译期错误，又不想给变量赋值，干脆清空了 return true; } } //代理 public class ProxyFactory implements InvocationHandler{ private Object lvar; public Object createLocalValProxy(Object obj){ this.lvar = obj; return Proxy.newProxyInstance(this.lvar.getClass().getClassLoader(), this.lvar.getClass().getInterfaces(), this); } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { LocalVar var = (LocalVar)this.lvar; Boolean bl = new Boolean(false); //里面去处理，返回true或者false return bl; } } //main LocalVar lv =new LocalVar(); ProxyFactory factory = new ProxyFactory(); LocalVarInterface lviface = (LocalVar)factory.createStudentProxy(lv); lviface.doNext();

[codingjav]

搞成静态的 http://www.iteye.com/problems/8679